Resin seal rings are now mass produced on the assumption that they are used in a sliding contact with polished surfaces, irrespective of qualities of mating housing materials. Various improvements of polished surfaces have been so far made to enhance the self-abrasion property of seal rings.
Patent Literature 1: JP-A-2002-317089
However, the users are now endeavoring to eliminate the polishing work of the mating housing materials to reduce the cost. Resin seal rings, on the other hand, are softer by nature than mating housing materials such as metals, particularly hardened metals obtained by quenching, etc., and thus are highly susceptible to abrasion, so that loss of seal ring function can be highly anticipated as a serious problem.